A spring probe pin assembly is often also referred to as a Pogo™ pin. Pogo™ is a registered trademark of Xcerra Corporation in Norwood, Mass. A spring probe pin or Pogo™ assembly is a device used in electronics to establish an electrical connection between two circuits. Pogo™ pins are usually arranged in a dense array, connecting together many individual nodes of two circuits or circuit boards. Pogo™ pin connectors are commonly found in automatic test equipment (ATE) in the form of a bed of nails where they facilitate the rapid, reliable connection of the devices under test. A Pogo™ pin connector may contain just a few Pogo™ pins to many hundred Pogo™ pins. In one extremely high-density configuration, the array takes the form of a ring containing hundreds or thousands of individual pogo pins; this device is sometimes referred to as a pogo tower.
Pogo™ pin connectors are also commonly used to form reliable, non permanent electrical contacts in electrical equipment. For example an electronic device with multiple electrical connections may be plugged into an piece of electrical equipment and secured in place for example by a snap connector, a spring, or screws. A Pogo™ pin connector may be used to establish electrical connection. An electronic device installed in electrical equipment in this manner may be easily be removed and replaced without the need of special equipment. This is especially convenient for repairing or updated electrical equipment in the field. For example, Pogo™ pin connectors are used for the installation of devices in the Cray 2 computer.
As shown in FIG. 1, a spring probe pin assembly 100 may have one movable probe pin 102 at one end of the cylindrical barrel member 106 and an immovable pin 116 attached to a closed end of the cylindrical barrel member 106. As shown in FIG. 2 the spring probe pin assembly 200 may have two movable probe pins, 202 and 216, one at each opposing open ends of the cylindrical barrel member 106.
The spring 108 forces the plunger 104 (or plungers 204 and 210 in FIG. 2) into electrical contact with the wall of the barrel member 106. As is illustrated by the arrows 112 in FIG. 1, the current typically flows from the probe pad on the integrated circuit through the probe pin 102, through the plunger 104, through the wall of the barrel member 106, and into the head 110 of the spring probe pin assembly (or the upper plunger 210 and the upper probe pin 216 in FIG. 2).
Although the spring 108 typically forms an electrical path in parallel with the cylindrical barrel member 106 of the spring probe pin assembly, the resistance of the spring is typically so much higher than the resistance of the wall of the barrel member 106 that an insignificant amount of current flows through the spring 108.
A common problem that may arise with a conventional spring probe pin assembly 300 during use is illustrated in FIG. 3. After repeated use, due to wear the contact 314 and 316 between the plunger 304 and the wall of the barrel member 306 may be degraded resulting in increased resistance. The increased resistance may result in an increase in current flowing through the spring 308. Current greater than about 200 mA through the spring 308 of a spring probe pin assembly 300 may cause the spring 308 to heat up and lose temper or may cause the spring 308 to melt.